1. Field of the Invention
The present invention generally relates to RF antennas and, more particularly, to RF antennas for mobile communication devices.
2. Background of the Invention
The Hearing Aid Compatibility Act of 1988 (HAC Act) requires that the Federal Communications Commission (FCC) ensure that telephones manufactured or imported for use in the United States after August 1989 are compatible with hearing aids. When the Act was passed in 1988, Congress specifically exempted from the hearing aid compatibility requirements “telephones that are used with public mobile services” (e.g. wireless telephones). To ensure that the HAC Act keep pace with the evolution of telecommunications, however, Congress granted the FCC the authority to revoke or limit the exemptions provided in the HAC Act for wireless telephones.
The use of wireless telephones by consumers in the United States proliferated significantly in the years following the HAC act, and by 2003 the FCC determined that continuation of the exemption for wireless telephones would adversely affect individuals with hearing disabilities. Moreover, the FCC also determined that providing a limitation on this exemption was both technologically feasible and in the public interest. Pursuant to these determinations, and acting under its authority granted by congress, the FCC implemented new rules for hearing aid compatibility applicable to digital wireless telephones. These rules became effective in 2005.
The new rules implemented by the FCC establish extended existing telecoil coupling requirements and established new limits on both electric and magnetic near fields generated by digital wireless telephones in the RF spectrum. Further, the rules mandate that a percentage of the digital wireless telephones provided by wireless manufactures and carriers must meet the near field RF radiation limits, and that these limitations must be met without compromising the overall performance of the digital wireless telephones for users with hearing aids.
An indicator of a wireless telephones performance is the telephone's total radiated power (TRP). TRP represents the amount of power radiated by a wireless telephone, and therefore roughly correlates to its broadcast range. Thus, to comply with the applicable FCC rules for hearing aid compatibility, digital wireless telephones should provide sufficient TRP while maintaining both electric near field radiation and magnetic near field radiation within the applicable limits specified by the FCC.